In recent years, a need to transform a hand-written word, figure, symbol, and so forth to electronic data that can be dealt by an information-processing device is increasing; especially a demand on a method with which a hand-written information is entered into a computer and the like in real-time without going through a reading device such as a scanner is increasing.
For example, a transparent sheet arranged in front of a display device, especially, a transparent sheet printed with a dot pattern which is capable of providing location information to show the location of an input trajectory by an electronic input pen and so forth, is disclosed (see, for example, Patent Document 1). This transparent sheet has the dot pattern printed by using an ink emitting the light that can be read by irradiating a light having a prescribed wavelength thereby having a function to provide location information by an input trajectory reading means. However, in Patent Document 1, there is no description as to a kind of the ink that can realize the transparent sheet like this, a direction of the printed surface, a way how to lay out the location information, or the like, so that there is no description as to the specific example of the transparent sheet; and thus, the description thereof is merely an idea or a desire of the transparent sheet.
On the other hand, a proposal was made about a transparent sheet printed with an infrared reflective pattern that can provide an information with regard to location of an input terminal on the transparent sheet, wherein the transparent sheet has a printed surface having a transparent pattern with an infrared light reflective regularity printed on surface of a transparent substrate, and this is installed in front of a display device capable of image-displaying such that the said printed surface may face to the device; the ink to constitute the transparent pattern contains an infrared-reflective material; and the transparent pattern is irradiated with an infrared light from the backside of the printed surface by using an input terminal capable of irradiation and detection of the infrared light thereby reading the reflection pattern of the infrared light (see, for example, Patent Document 2).
In addition, an electronic pen-writing paper is proposed, wherein the electronic pen-writing paper is used for a data-input system to transmit a dot pattern from a transmitting unit to an outside communication device, the said dot pattern printed around the place where an electronic pen is put on being read by a sensing unit that is built-in the electronic pen when an information is written on an information-writing surface by the electronic pen; and if a figure pattern other than the dot pattern is printed on the information-writing surface is printed, the dot pattern is printed firstly, and on it is printed the figure pattern (see, for example, Patent Document 3).
Further, a printed sheet is proposed, wherein the printed sheet is a laminate having a substrate, a regular pattern-printed layer, a primer layer, and a surface protective layer in this order; an ink to constitute the printed layer contains a colorant; the printed layer can provide an information with regard to location of an input terminal on the printed sheet by reading the pattern from the side of the surface protective layer by using a pattern-detectable input terminal; the surface protective layer is a hardened filler-containing curable resin composition; and the 60° gloss value is in the range of 8 to 20 (see, for example, Patent Document 4).
The infrared reflective pattern-printed transparent sheet disclosed in Patent Document 2 is used by installing in front of a display; and the electronic pen-writing paper disclosed in Patent Document 3 is used as an input pad.
During the time of a lecture, a conference, and so forth, in order to make them interactive, it may be sometimes necessary to project a hand-written word, figure, symbol, and the like on a projection screen through a projector or the like after these informations are transformed to electronic data. In addition, it would be very useful if it is possible to project a document, which is directly written in the projected figure on a projection screen, through a projector after it is taken-in in real-time as digital information.
On the other hand, in the case that it is not necessary to make the conference interactive such as those mentioned above, for example, in the case of brainstorming, the projection screen may be used effectively as a writing board like a white board.
The equipment having many functions aggregated as a projection screen and a white board as mentioned above is very useful not only because various uses may be covered by single equipment but also because a space in a conference room may be conserved.
However, practically it is not an easy task to simultaneously satisfy the functions as a projection screen and a white board without impairing the functions as a printed sheet.
Accordingly, the projection screen using the printed sheet disclosed in Patent Document 4 was revolutionary because it had the function as a white board simultaneously.
In the case when a dot pattern is printed on a substrate of the print sheet, a gravure printing method is desirable because of fast printing speed and high productivity; but it has been difficult to obtain a dot pattern readable with high reading precision in a prescribed dot size (dot diameter in the range of 80 to 130 μm) by means of a gravure printing method.
In addition, in the case of the gravure printing method, when a dot pattern is formed by printing in the prescribed area, because a doctor is used, there is a phenomenon that an ink to print the dots spreads out to the printing direction toward the area where the dot pattern is not formed in the boundary of the posterior edge of the dot pattern-formed area in the boundary between the dot pattern-formed area and the dot pattern-unformed area, thereby causing a problem of unstable reproducibility in printing of the pattern edge. As the reason for this, it is presumed that during the time of scraping off the excess printing ink filled in the cell to form the dot pattern by the doctor blade, the doctor bounces in the boundary with the dot pattern-unformed area so that the printing ink cannot be scraped off sufficiently in the posterior edge in the printing direction.
On the other hand, printing of the dot pattern by a digital printing method such as an ink jet printing method is prone to give a more precise dot size as compared with the gravure printing method; however, the practicality thereof has been low because of slow printing speed and poor productivity.
Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-256122
Patent Document 2: Japanese Patent Laid-Open Publication No. 2008-26958
Patent Document 3: Japanese Patent Laid-Open Publication No. 2008-173859
Patent Document 4: Japanese Patent Laid-Open Publication No. 2011-95706